My only feedback would be to increase the number of free champions. With the rate you're adding new ones the base 10 free seems a little short in comparison to how many are actually available.

your supposed to play the game and unlock them as you go.... the 10 champions is fine it is just to give you a selcetion to see what you like. then if your really like one you buy it. pretty soon you should have them all. and by soon i mean like in a year